add-apt-key Alternatives
add-apt-key is described as 'This command line tool can be used to add a GPG key to your APT key ring' and is an app. There are three alternatives to add-apt-key for Linux and OpenPGP. The best alternative is Y PPA Manager, which is both free and Open Source. Other great apps like add-apt-key are launchpad-getkeys and Introduce PPA.
Y PPA Manager is a GUI tool to add, remove, purge, list and search for Launchpad PPAs. It works with Ubuntu and Linux Mint.
Discontinued
Y PPA Manager was last updated in 2013 and no longer works.
Launchpad-Getkeys is a script (comes packaged in a .deb) that automatically imports all missing GPG keys, even if you're behind a firewall.
The program saves you from having to open the console to add a new PPA. You can add the new repository in two ways. Introducing the ppa and then the name of the application or pasted directly the code from any web
Discontinued
No update since 2011 plus dead links on home page